Electrically-heated device



May 20, 1924. 1,495,045

W. A. RANKIN ELECTRICALLY HEATED DEVICE Original Filed Dec. 18, 1920 2 Sheets-Sheet x lnventgr- William ARanRin, fg%%ju- His Attorneg May 20, 1924. 1,495.06

W. A. RANKIN ELECTRICALLY HEATED DEVICE Original Filed Dec. 18 1920 2 Sheets-Sheet 2 Fig.7

Patented .May 20, 1924.

UNITED STATES- 1,495,045 PATENT OFFICE.

WILLIAM A. RANKIN, OF CHICAGO, ILLINOIS, ASSIGNOR TO EDISON ELECTRIC APPLIANCE COMPANY INC., A CORPORATION OF NEW YORK.

ELECTRICALLY-HEATED DEVICE.

Application filed December 18, 1920, Serial 110.431,?57. Renewed I Ieeember 8, 1988.

To all whom it may concern:

Be it known that I, \VILIJAM A. RANKIN, a citizen of the United States, residing at Chicago, in the county of Cook, State of Illinois, have invented certain new and useful Improvements in Electrically-Heated Devices, of which the following is a,specification.

My invention relates to electrically heated devices such as ovens and the like and has for its object the improvement of such devices whereby their operation is rendered automatic.

In one aspect my invention comprises an improved electrically heated device such as,

an electrically heated oven in which the heat is automatically applied and cut off at predetermined times. My arrangement is such that the operator mayset the apparatus in advance and the operations will thereafter take place automatically when a predetermined time has arrived.

My inventionincludes timing means of an improved character having certain valuable characteristics prominent among which is the ease with which it may be started and stopped. In one form of my invention the arrangement is such that the timing device" is automatically started when the timing deyice is set and'is stopped when the current 15 finally cut off from the oven.

In another aspect my invention comprises an improved arrangement which embodies both time and temperature control, so. that the temperature 1s maintained approx1- mately constant=during the time the current is applied. The temperature control is effected by an improved thermostatic arrangement which enables the operator to conveniently determine the temperature which 'shall be reached in the oven. In other words, the o erator knowing the temperature required: sets the a paratus for that temperature. Knowing also the time which the cooking operation will require at that temperature and havin in mind the time at which the operation s ould be completed, the operator sets the device so' that the heat will be applied in time to insure the completion of the full cooking operation.at the proper time. The operator may then leave the aaratus to take care of itself. I t 5.. A

tion will appear in the course of the following specification in which I have disclosed objects and purposes of my inven-- my invention embodied in concrete form for purposes of illustration. i In the accompanying drawings illustrat- 111g my invention Fig. 1 is a view'of an electric range having an oven equipped with my improvement; Fig. 2 is a plan view of my lmproved thermostatic arrangement; Fig. 3 is a side view thereof looking in the direction of the arrow (Fig. 2) Fig. 4 is a sectional view of the thermostatic switch mechanism; Fig. 5 shows the arrangement of the'thermostatic element; Fig. 6 is a side view of the same and ig. 7 is a diagram of the circuit connections. Referring first to Fig. 7 it will be seen that I have shown a number ofheating units H, H, H H which, it will be understood, are located within the oven, which is preferably heat insulated (not shown) in a well understood manner. The electric circuit to these heating units is controlled by a timing device which serves asa clock and which I shall designate by the letter C. The circuit to the heating unit is also controlled by a thermostat designated by the letter T. The thermostat T and the timing device- 0 are in series so that the circuit must be completed through both the timing device and the thermostat before the circuit will be completed to the heating unit. The direct control of the current to the heating devices is through an electromagnetic switch 10, the circuit of which is controlled by the timing device and the thermostat. The arrange ment of the heatin units in the circuit is controlled by. a pIurality of switches 11 and 12. w

The timing device which I have illustrated in a conventional way is an electrically driven device. The particular form of this timing device forms no part of my present invention, since it is fully described and claimed in an application of Chester I. Hall, Serial No. 396,749, filed July 16, 1920. I

'have merely shown the essential elements of by pinions 16 and 17. These gear wheels 14 and 15 are provided with openings 18 and 19 adapted to receive projections 20 and 21 mounted upon spring pressed switch members .22 and 23. The arrangement is such that when the gear wheels reach the proper position with reference to the pro ections 20 and 21. the projections will enter the openings and operate the contacts 24 and 25 associated with the switch member. These gear wheels 14 and 15 are preset 1n the proper position so that their openings will arrive at the point opposite the projections at the proper time by means of knurled wheels 26 and 27 provided with pointers 28 and 29 and a dial 30 cooperating with the pointers to indicate the position of the gear wheels. As, illustrated, the gear wheel 15 is connected with the knurled wheel 26. by a sleeve 31 fitting over a shaft 32 to which the pointer 29 and knurled wheel 27 (are connected. Springs 33 and 34 press gears 14 and 15 respectively to the right and into. the positions shown in Fig. 7. It Wlll be understood that by pressing on either of the knurled wheels26 and 27, the gears will be moved out ofmesh with the pinions on the motor shaft against the pressure of springs 33 or 34, and the gear wheels may then be turned freely so as to place the openings therein in proper positions as indicated by the pointers. Contacts 25 are open when the projection 21 is in its opening and contacts 24 are closed when projection 20 is in its opening. I I

' It will be further understood that I have shown parts of this timing arrangement merely for purposes of illustration and have not attempted to show or describe the 'ez act details of operation of the timing device.

The operation of the parts as thus far described will be as follows :When the operator wishes to set the device for automatic operation he .will turn the knurled wheel 26 until the pointer 28 indicates on the dial the time when the heating unitsare to be cut out of circuit, that is, when the heat is to be turned off from the oven. In doing so he presses on the knurled'wheel 26 so as to release the gear 15 from its pinion and turns the knurled wheel, thereby moving the projection 21 out'of the opening 19 in the gear 15 leaving'it pressedagainst the face of the gear. This closes the contacts 25 andstarts the motor 13, the circuit being from the positive side of the. line through contacts 25,

' winding of the motor 13 and back to the he ative side of the line. The operator also ad usts the pointer 29 to a position on the dial corresponding with the time when the current should be turned on. This action removes the projection 20 from its opening andopens the contacts" 24. Assuming that the pointer '29 has been turned to four 24, theremostat T, winding of conta'ctor 10 to the negative side of the line. This causes the contactor 10 to close and connect the heating units in circuit. The heat is now on in the oven. lVhile the-heat is on in the oven the thermostat, which is preferably located within the oven will maintain the ten'lperature substantially constant by opening' and closing the circuit at contactor 10. When the hour of six oclock arrives the projection-21 will enterits opening thereby opening the contacts 25 to permanently deenergize the contactor 10 and cut off the heat ing units. The opening of the contacts 25 also stops the motor 13 leaving the projections 20 and 21 in their openings.

It will be noted that the gears 14 and 15 are mutilated so that when the projections enter the openings of the gears the smooth part of the gears will be opposite the pinions so that the gear can be stopped without in terfering with the rotation of the motor.

Referring now tothe construction of the 'themostatic switch shown in Figures 2 to 6, the thermostatic member proper 35 (Figs. 5 and 6) consisting of an elongated strip or blade'ofthermostatic metal is mounted on a stationary support 36 within the oven as shown in dotted lines (Fig. 1). As shown,

with a slotted member 39 which receives a pin 40 which is adjustably secured in the support 36. On an increase in temperature the thermostatic strip will bend in the formof a bow, as shown in dotted lines in'Fig. 5, thereby turning the shaft 38 to which the wide end of the element is screwed. Turning now to Figs. 2 t0 4, it will be seen that a switch operating arm 41 is secured to the shaft 38 so that as the shaft turns it will turn the arm 41. This arm is provided with a sector 42 which isadapted to engage a switchlever 43 mounted upon an ad ustable arm 44. This arm 44 has a hub 45 in which the shaft 38 turns so that the rotation of the shaft 38 does not affect arm 44. A quadrant 46 is provided to act as an out- .side support for the shaft 38 and the arms or 48 cooperating with this scale and the arm 44 is provided with a similar pointer 49' gd-a projection 50 which acts;

as an adjusting handle for. the arm. By

' is engaged by a spring pressedpawl 52.on

means of this projection 50, therefor, the

arm 44, which carries with it the switch mechanism, may be adjustedto theproper position as indicated on the scale 47 at which the switch will be operated and the circuit of the contactor 1O opened. The quadrant is provided with a notched portion 51 which the arm 44 for holding the arm in various positions. 3

. The construction of the switch mechanism ber 57 having a pointed end. This pointed- Y stri proper is shown in detail in Fi 4 as consisting ofv an elongated block 0 insulating material 53 secured to the end of the arm 44. Pivotally mounted upon this block is a switch lever 43 which operates the contacts cont-rollingthe circuit of contactor 10. As shown, the switch lever 43 which is not the contact. lever, is provided at its outer end with a roller 54 to be engaged by the sector 42. At its middle point the lever 43 is provided witha screw 55 engaging a ball 56 which in turn engages with a sliding memend of member 57 engages a spring contact 58 which is normally in engagement wit contact screw 59. When the switch lever 43 is engaged by the sector 42, the screw forces the member 57 inward and this in turn forces the contact spring 58 away from the contact screw 59 to break the circuit of the contactor 10. When the sector 42 is not in en agement with the roller 54 of switch 43 the contact spring 58 moves into engagement with the contact screw 59 to close the circuit of contactor 10 and forces the switch member outward so that the switch member 43 is normally in a position to be engaged and forced inward bythe sector 42.

' As thus constructed and arranged, the op eration of my device is as follows: Assuming that the opeator wishes to have the current automatically turned on at four oclock so that the oven will be heated and that it is desired that the curre-n be turned ofi at six "'oclock, the operator will setthe. inter 29 at the time indicated bn the dial 30 at which it is desired that the current shall be connected so that the circuit of the heating units shall be closed at four oclock. This is done, as before stated, by pushing in on the knurled head 27 and turning the I so '- erat'or also sets the pointer on an arm 'six oclock, the time when the circuit is to be opened, and the contacts" 25 are therefore closed. This starts the timing device which in this case isan electric motor 13. The 0%)- means of the handle 50 to the temperature at which the cooking operation is to take place; say, for instance, 400 degrees. Since the oven is then cold, the arm 41 and pointer 48 will be in the zero or lowermost position (Fig. 2). VVhen the temperature of the oven reaches substantially 400 degrees, the arm 41 will have advanced to a point where the sector 42 on the arm 41 engages the roller on the'switch lever 43 and opens the circuit of the contactor 10, thereby cutting ofi the current. The temperature of the oven now starting to decrease, the arm 41 will move back and allow the switch 43 to again be embodied in concrete form and as operating in a specific manner in accordance with the provisions of the patent statutes, it should be understood that I do not limit my invention thereto since various modifications thereof will suggest. themselves to those skilled in the art without departing from thespirit of my invention the scope of which is set forth in the annexed claims.

What I claim as new anddesire to secure by Letters Patent of the United States, is

1. An electrically heated oven or the like comprising a baking chamber, electric heatingunits therefor, thermostatic means for controlling the heating units, a normally inoperative timing device controlling. thecomprising a baking chamber, electric heat- I ing units therefor, thermostatic means for controlling the heating units, a normally inoperative timing device controllin the circuit through the heating units an thermostat; a manually controlled member" for starting said timing device, means for presetting the time at which the timing device will connect the heating unitsand thermostat in circuit, and means whereby at a predetermined time after such presetting the member will be automatically erated to disconnect the heating units and stop the v timing device.

3. The combination with an electrically heated oven or the like of a thermostatic device for controlling the samecomprising a thermostat member located within the oven, a switch movable to various temperature positions outside of said oven and a member operated by s'aidthermostatand cooperating with said switch in its various positions to operate the switch at the temperature at which the switch is set. r

4. The combination with an electrically heated oven or the like of a thermostatic device for controlling the same comprising a contact device for controlling the heating units and mounted to rotate outside of said oven to various-positions, an indicator c'ooperating with said switch to act as an index therefor and a member operated by the thermostat over substantially the same range as said-contact device and cooperating with it in its various positions to automatically operate the contact.

5. The combination with an electrically heated oven or the like-of a thermostatic device for controlling the same comprising a member mounted to rotate outside of said oven to various positions, a temperature indicator cooperating with'said member to act as an index for presetting the same, a second member operated by. the thermosatic element over substantially the same range as said first member, a contact device on one of said members and means on the other member for operating the contact device in the various presetting positions.

' 6. The oombinatlon with an electrically heated oven or the like of means for controlling the same comprising a thermostatic element within the oven, a switch rotatably mounted outside of the oven for adjustment to various positions and an actuating member for the switch operated by the'thermowhereby the temperature within the oven is indicated.

8. The combination with an electrically heated oven or the like of a thermostatic de: vice for controllin the same comprising a thermostatic member located within the oven, a circuit controlling device including a switch and an operating member therefor, one of the members of said device being adjustable to various positions and the other cooperating therewith in its various positionsto operate the switch at the temperatugfi corresponding with the position occu- 1 I p I witness whereof, I have hereunto set my hand this tenth day of December, 1920.

WILLIAM A. RANKIN, 

